I think my drive unit bolts may be loose. How tight should they be? Is there a torque setting?

You should not overtighten the fixings of the drive units as it can distort the chassis or damage the bolt’s thread.
The best solution is use a torque wrench using the following settings in Nm:

      Drive Unit type  
         
Model     HF MF LF
         
twotwo series   0.5   0.75
twotwoSub2       3
IB1, IB1S, IB1S-A    0.75 0.75 3
DB1 Gold    0.6   0.75
25 & 25i series    0.6 0.75 0.75
fact & fact signature    0.6 0.75 0.75
fact fenestria    0.75 3 1
IB2 SE    0.6 1 1
MB2/BB5 SE     0.6 1 3
IB2S Active & Passive    0.6 1 1
MB2S Active & Passive    0.6 1 3
BB6 Active & Passive    0.6 1 3
ci series   0.5 0.6 0.6

If you are unsure or need assistance please contact our service department for further information – service@pmc-speakers.com